echols



. Patented June 2o, |8994. as. EcHoLs.

METAL WORKING MACHINE.

(Application filed June 13, 1898.)

4 Sheets-Sheet l.

` (No Model.)

*i Inventor.'

. HW 1Min ummlnnmm NIJ No. 627,299. Patented June 2o, |899.

F. G. EcHoLs. `METAL WORKING MACHINE.

(Application led June 18, 1898.) QNo Model.) y v 4 Sheets-Sheet 2..

Wi m esse@ ,.No. 627,299. Patented June 2o, m99.

F. G. ECHLS. METAL WORKING MACHINE. (Application filed June 13, 1898,) No Model.) 4 Sheds-Sheet 3.

Y252 vez? for."

No. 627,299. Patented lun"e 20, |899.

` F. G. ECHOLS.

METAL WORKING MAGHINE.k

' (Application filed June 13, 1898.)

lNo Model.) 4 Sheets-Sheet 4.

'Ill/ll ll... Iii

e il A Y Y ilwrrnn @rares FRANK Gr. ECI-IOLS, OF HARTFORD, CONNECTICUT, ASSIGNOR TO THE PRATT da VIIITNEY COMPANY, OF SAME PLACE.

VIETALWORKING MACHINE.

SFECIFICATION forming' part of Letters Patent No. 627,299, dated June 20, 1899.

Application filed June 13, 1898. Serial No. 683,271. (No model.)

To a/ZZ whom it' may concern.-

Be it known that I, FRANK G. EoHoLs, a citizen of the United States, residing in Hartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Machines for Removing the Teeth ot' Screw-Threading Tools,iot`` ting tap to form the improved tap described and claimed in Patent No. 588,056, granted to me August 10, 1897. In the tap described in this patent the tool has an odd number of wings, and each wing has vone-half the usual number of teeth, one-halt` of all the teeth of the tap being entirely removed, preferably by cutting away alternate peripheral teeth, allot' the teeth being located in a single spiral from end to end of the tap. A machine suitable for forming this improved tap is shown, described, and claimed in my prior patent, No. 602,062, granted April 12, 1808, which machine is intended to operate an ordinary chasing tool or cutter for removing alternate teeth from the wings of the tap. In the machine shown, described, and claimed in the present application, however, my improved tap is intended to be formed by cutting away these alternating teeth by means of a milling-cutter; and one of the main objects of my present invention is the pro vision,`

in connection with a suitable rotary Workholder or tap-holder, of a tool-holder on which is mounted a rotary milling-cutter capable of adjustment relatively to the longitudinal axis of the tap to bring the cutter into position for milling teeth of different pitch for different taps, suitable means being employed for shifting the tool-holder toward and from the work-holder a plurality of times during each rotation of a tap in order that the millingcutter may be shifted into and out of engagement with teeth of alternate wings of the tap.

In connection with suitable means for rotating the Work-holder, and hence the tap, and for advancing the milling-cutter up to and withdrawing it from the work I will also employ, ordinarily, feeding means for imparting a traveling movement to the tool-carriage on which the milling-cutter is intended to be mounted in order to permit thecutter to operate upon the teeth of the tap `not only at separate points in the periphery of the work, but also at different points in the length of the latter, and follow the spiral in which the teeth of the tap are located.

As it is customary in milling to advance the milling-cutter toward the work somewhat slowly, I prefer ordinarily to make use of a low-speed feed mechanism for imparting this advancing movement to the cutter during the milling of the work; but such a slow return movement to the idle position of the cutter is undesirable not only for the reason that time is wasted in thus retracting the cutter slowly, but also because it would be extremely diiiicult in milling teeth in alternate wings of the tap, as this machine is intended to do,

for the cutter to clear. the Win g of the tap on which it does not operate and to withdraw from the work in time to prevent striking such wing, which of course would result in interfering with the proper action of the mechanism. Nhen the milling-cutteris withdrawn from the work, however, at a higher rate of speed than that which is employed to advance it, the `cut-ter will readily clear the intermediate uncut wing before the tap in its rotation can come into position for such intermediate wing to strike the teeth of the milling-cutter. Hence an important feature of my present improvements is the employment of diiferential feed mechanism for imparting somewhat slow advancing Inovements to the milling-tool during the cutting action and a relatively rapid return movement to such tool to prevent marring of the work, injury to the cutter, and possible damage to other parts of the mechanism. This differential feed mechanism may be of any suitable type; but I prefer to employ for operating the tool-holder upon which the milling-cutter will be mounted a pair of driving members operative alternately, the low-speed one to advance the cutter while it is in action and the high-speed one to return it after it has finished the milling of a tooth in a wing Awn Y the Work-holder and tool-holder will of course of the tap, and in connection with this highspeed actuating means for returning the cutter to its idle position I prefer to employ also a quick-let-off device, such as a cam and an operating-spring, the cam serving to permit a quick return movement of the cutter at the proper time and the spring to retract the tool- -holder, and hence the cutter, positively and quickly the moment it is released by the cam.

For the purpose of rendering the machine entirely automatic in its action I prefer to employ in connection with the differential driving members ofthe differential feed mechansm a clutch or coupling which may be of any suitable type, controlled in its Inovements by therotation of a driven member actuated first by one and then by the other of the two driving members with which such clutch cooperates. In the preferred construction the clutch will engage the driving members 4alternately to the driven member', and a suitable slide operated at intervals in the rotation of the driven member will reciprocate the clutch member to its respective clutching positions. The manner in which this is accomplished will be described in detail heref inafter.

In cutting plain taps having straight sides maintain the same relative distan ces between them at the initial points of the several cutting operations; but in cutting taper-taps I this interval should vary in accordance with the taper of the tool. `lIence in cutting away the teeth of taper-taps I make use, in connection with the instrumentalities hereinbefore mentioned, of a guide disposed at an angle to the longitudinal axis of the work-holder, the angle of inclination of the guide corresponding, of course, to the angle of taper of the tap.

These and other important features of my improved machine not hereinbefore set forth will be hereinafter described in detail.

In the drawings accompanying and forming part of this specification, Figure 1 is a plan of a metal-working machine constructed in accordance with my present improvements. Fig. 2 is a side elevation of the same. Fig. 3 is an enlarged transverse section of the same with parts broken away, the section being taken in line 8 3, Fig. 1, this View illustrating the tool-holder retracted and the milling-cutter in its idle position. Fig. t is an enlarged end view of the machine as seen from the left in Fig. 1. Fig. 5 is an enlarged transverse section of the machine with parts broken away, the section being taken in line 5 5, Fig.

1. Fig. 6 is an enlarged transverse section of the machine similar to that shown in Fig.

`3, but with the parts in the positions which they assume when the milling-cutter is in its advanced or working position. Fig. 7 is an enlarged section of the machine, the section being taken in line 7 7, Fig. 1. Fig. Sis an enlarged sectional detail illustrating the toolholder, the milling-cutter, and the driving means for the latter, the section being taken on the line S 8, Fig. 2. Fig. 9 is an enlarged longitudinal section of the main driving-spindle or work-spindle and'the parts carried thereby, and Fig. 10 is a detail of the chuckcenter or collet for engaging and holding the tap in the work-spindle. l

`Similar characters designate like parts in all the figures of the drawings.

The several operative parts of my improved machine' will be mounted ordinarily upon the usual bed B, and many of these working parts are substantially similar to those in metal- Working lathes in common use. Among these may be mentioned the tail-stock T, which slides on ways 5 in the usual manner, the head-stock Il, the work-spindle 6, and the lead-screw 7, supported for rotation in the bed of the machine and connected with the tool-carriage for imparting to the latter a traveling movement longitudinally of the bed of the machine. The lead-screw receives its movement in this case from the work-spindle G'through a spur-gear 6', which meshes also with a gear-wheel 8', supported on a stud 8, which also carries a second gear-wheel S", meshing with the gear-wheel 9', secured to a sleeve or spindle 9, journaled in this case for rotation on the work-spindle 6, and the movement of the gear 6' is in turn transmitted through either one of a pair of pinions 10 and 10 to a gcar-wheel12, suitably supported and driving a pinion 12, which meshes with a large gear-wheel 13, which in turn drives a gear '7' on one end of the lead-screw. The large gear-Wheel 13 is adjustably supported in this case on an adjustable arm in the usual manner to permit ofthe use of change-gears, and the two pinions 10 and 10 are also supported in a well-known manner on the end o f an adjustable rock-arm 15', projecting from a short shaft 15, on which the gear 12 and the pinion 12 are carried. (See Figs. 2 and 4.) It Will be apparent, of course, that when the pinion l0 is in mesh with the gear G' the leadscrew will be turned in one direction, while when the pinion 10' is in mesh with said gear b" the movement of the lead-screw will be reversed. These devices just described of course constitute the feeding means for actuating the tool-carriage, and hence the toolholder, longitudinally of the machine.

For the purpose of rotating the work-spindle 6 I prefer to make use of differential driving mechanism, and hence I have illustrated at P and P a pair of driving members. The former in this case may be a cone-pulley having three steps or pulleys p, p, and p" for driving the mechanism at a low speed, an intermediate speed, or a high speed, while the pulley P when operating will always, act as ahigh-speed driving member. Ordinarily either the pulley p or p will be employed, and the pulley p will be used only for very light work. The two driving members or pulleys P and P are intended to be alternately effective and will be continuously rotated in the same direction by suitable belts,

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as indicated in Fig. 2. For the purpose of engaging these driving members alternately to a suitable driven member of the machine shaft 17 is intended to transmit its movement directly to the work-spindle 6, which carries the tap to be cut, and in this case the inner end of said shaft is supported in a long bearing in the head-stock II, (see Fig. 5,) a portion of the body of the head-stock being cut away to form cheeks for holding firmly in place a Worm 18, carried by the driven member or shaft 17, which worm in turn drives a Worm-gear 19, secured to the workspindle 6.

The work or tap tis supported in the usual manner between the head-stock and the tailstock, the work-spindle 6 being in this case vhollow for the greater portion of its length and having a flaring innerend adapted to receive a chuck-center or collet c, the inner end of this Work-spindle being externally screwthreaded in this case to receive a nut .n for wedging the chuck-center in place and for loosening the same. This chuck-center may be released by means of a spring s and is preferably divided at both ends thereof, as shown clearly in Fig. 10, in order that it may grip the shank of the tap firmly at two Widelyseparated points in the length of such shank.

The tool-carriage is designated in a general way by C and is supported in the usual manner on ways 5 for traveling movement longitudinall y of the machine. This tool-carriage is made up of severalparts; but the tool-carriage proper is intended to support a transversely-lnovable slide and also a tool-holder, which may be mounted directly on the tool slide.

The tool-holder may be of any suitable construction, and it will-be so mounted as to have a movement for shifting the milling-cutter toward and from the work-holder intermittently, the movement of said tool-holder being so timed that the tool or cutter will be shifted back and forth .a plurality of times during a single rotation of the work-spindle. The movement of the tool-holder for carrying the cutter toward and from the work-holder and into and out of engagement' with the work may advantageously be a reciprocatory one, the tool-holder, which is indicated herein in a general Way by 7l, being mounted in this case on a tool-slide 21, secured to a slidable operating-bar 22, having at its opposite end a shoe 22', working in a taper-guide 23 of the usual type. By means of this taperguide and the connections lto the cross-feed slide or tool-slide 21 the latter may be operated to impart the proper taper-feed movement to the cutting-tool.

While the cross-feed slide 21 serves as a means for imparting a taper-feed movement to the cutter, it does notin this casesupport the latter directly; but instead the cutter is carried bythe tool-slide proper, h, which is intended to be capable of shifting quickly from its working to its idle position in order that the cutter may clear any tooth of the tap which is not to be milled.

The tool-holder 7L may consist of several main parts, although it is only essential for the purpose of adjusting the milling-cutter at any desired angle to cut teeth of different pitch that it should be slidable toward and from the work and should also be so mounted as to permit it to tip in the direction of the axis of the tap; but in the present case the toolholder preferably consists of a main supporting-slide, such as 23, mounted on the toolslide 21, an adjusting tubular slide, such as 2 4, supported on the slide 23 and movable back and forth to enable the operator to adjust the cutter up to and away from the Work, and a tool-holding cylinder,such as 25, mounted to turn in said tubular slide. Hence although the tubular slide 24 has an adjustment on the supporting-slide 23, yet it is not essential that more than one part be so used for obtaining a reciprocating or back -and-forth movement of the tool-holder with respect to the Work, and therefore said tool-holder may be considered as a duplex one, consisting, essentially, of a slide shiftable on the tool-slide or cross-feed slide 21 and a tool-holding member adjustable in an arc of a circle. The adjustment of the tubular slide 24 on the supporting-slide 23 may be effected in any desired manner, as by means of the adjustingscrew 2G. (Shown in Figs. 3 and 7.)

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Any suitable means may be employed for I holding the cylinder 25 in its adjusted position; but I prefer that the cylinder have a shoulder or iiange at its forward side, as indicated at 25', which shoulder abuts against the forward end of the sleeve 24, while at the rear end of the cylinder the latter may be screw-threaded and carry a nut 27 and a washer for gripping the rear face of the tnbular slide.

The shoulder 25 ofthe cylinder 25 mayhave an index thereon, as indicated in Fig. 8, cooperating with a pointer or mark on the tubular slide 24 for enabling the operator to set Vthe cutter at any desired angle to correspond carried is indicated by 28 and may be held inv place firmly by means of suitable check-nuts,

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4 @sarge said spindle having thereon in this case a Worm-Wheel meshing with a Worm 29',secu.red to azdriving-spindle 29, journaled in a bearing 30, projecting from the bracket said driving pulley or pulleys being carried by the spindle 29 and rotated from any proper source.

In order to impart to the tool-holder the quick returnmovement hereinbefore referred to, I prefer to introduce between the supporting-slide 23 and a fixed portion of the toolslide or cross-feed slide 2l a strong spring, such as 3l, which will force the tool-holder quickly away from the work, as when said tool-holder is released by the cam-actuator controlled by the driving mechanism. In the preferred form thereof this cam-actuator is a cam-wheel preferably of the type shown at W, and in this case it will be secured to the driven member or sleeve 9*,which is mounted on the work-spindle 6, and hence said camwheel, as well as its supporting sleeve or shaft,will be rotated by thedriving mechanism through the medium of the gear-train hereinbefore described' at a different rate of speed from that of the work-spindle. In the construction shown a two-to-one gear-train. is interposed between the work-spindle and the sleeve 9, and hence the former will be rotated twice as fast as the sleeve, and therefore twice as fast as the cam-Wheel. The purpose of this is to enable the tap to be rotated through an arc twice as great as thatthrough Which. the cam-Wheel rotates at each operation in order that every. other wing of the tap may be skipped by the cutter and the teeth of the tap cut away only on every wing of vthe tap as the latter rotates. In the construction shown thecaln-wheel has several sets of cams, and the cams of veach set are equidistantfrom one another; but at present it is only necessary to refer to the cams of the outer set, as

these are the-ones by means of which thetoolcarrier is shifted intermittently toward the work. The cams of this outer set are indicated in a general way by w and in the construction illustrated coactl with a rock-arm 35', secured to a rockeshaft 35, journaledin bearings at 36 and 37, the former being carried bythe head-stock II and the latter by the tool-carriage C. Between the bearing 3.7'v

and the tool-holder the shaft 35 is connected by means of a universal coupling, such as38, with a short,shaft 39, supported in bearings 40 and 4l, carried by the tool-slide or crossfeed slide 2l. Owing to the fact that the cross-feed slide has a taper-feed movement cured to the shaft 35, having in this case a fthe shaft 35 regardless of the transverse position ofthe cross-feed slide. The movement 3. of the shaft 39 may be transmitted to the tool- -holder in any suitable manner-as, for inf stance, by a rock-arm 39', secured to the .rockf shaft 39 and working in contact with a suitable iixed part of the supporting-slide 23.

-Vthen the rock-arm 35' is in the position shown in Fig..6, of course the arm 39' will take a corresponding position and will hold the cutter in engagement with the workholder. When the rock-arm 35 is released :by the quick-letfoff lface of the cam w, the

spring 3l will become edective to shift the i tool-holder back quickly to carry the cutter toits idle position and clear the next Wing of v the tap. Itwill be noticed that the shaft 35 hasa long keyway therein and that the rockr arm, 35' is splined on lthe shaft in such a manner as to permit the latter to move freely as the tool-carriage travels on thebed. Two other sets of cams maybe carried by the cam- Wheel W for the purpose of con-trolling the clutch by which the driving-pulleys P and P' are throwninto action alternately. The cams of these two sets are designated, respectively, l by fw and w, andfthey may be cam-segments detachably secured in concentric grooves in one faceof the cam-wheel. The cams w' conitrol the clutch when thel pulley P' is to be thrown into action, whilethe cams w" determine the operation of any ofl the pulleys of thehigh-speed cone-pulley P. In the conistructionV illustrated the cam-faces of these two sets of cams face in opposite directions, and between them is intended to work a iclutch-controlling member, which may be a flpin, such as 45', carried by an arm 45, seicured to a short sleeve journaled on a stud 46, projecting fromv a short post 47 rising from the head II of the machine. This arm 5 45 has a movement-transmitting member or finger, such as 45", controlling'the movement of a slide, such as 50, supported for reciproi cation in a slideway disposed transversely to the axis of the camshaft or sleeve, this slide carrying a member which controls directly the movements of the clutch 16. In the present case this member -or clutch actuator 1:which is carried by the slide may advanta- .geously be a spring-pressed bolt or. similar ipart, such as 5l, having a substantially argrow-sh-aped or cam-faced point cooperating i with another member connected with the clutch, which member may be the usual shifting lever 52, pivoted on the head H. In the IOO IIO

present case this lever and the spring-pressed from the lead-screw, of course the tool-carbolt or pin l are' disposed substantially in alinement with each other when in their working positions, the bolt being disposed. transversely to the slide 50 and mounted in a suitable opening or aperture therein.

The spring which operates the pin or bolt 51 is` preferably a strong helical one which will resist t-he tendency of the lever 52 to push back the bolt when the clutch is to be released t from engagement with one of the pulleys P and P', but which of course 'will yield at the 4end of the stroke of the lever 52 when the side face of the lever 52 and engage the opposite side, the working end of `this lever being also preferablypointedorsubslantiallyarrowshaped. while thel shifting lever is a fixed abutment and the bolt movesfor example, from the position shown in Fig. 1 to the opposite side of the lever 52-the latter will be shifted at once, owing to the power of the spring, to the opposite position and will uncouple the clutch 16 from the pulley P and shift said clutch into working engagement with the low-speed driving member or pulley P. This operation is entirely automatic and takes place on both movements of the bolt 51, thereby resulting in the shifting of the lever 52 in opposite directions alternately to couple and uncouple the said driving members also alternately. Ordinarily the bolt 51 should work properly to shift the lever 52; but as it is liable to stick occasionally l prefer to employ in connection with this clutch-actuator secondary actuating means, which may be one or more fixed bearing-faces, such as 55, on a suitable part of the head H of the machine and adjacent, preferably, to the head of the bolt 51, these faces being disposed substantially at the ends of the range of movement of the bolt with the slide 50. It will be evident that these faces are slightly rounded, as is also, preferably, a projecting head or other part 5l of the bolt 51. When the head 51' comes into engagement with said bearing-face, even if the bolt should stick it will be released immediately by the positive cam action exerted on the head of the bolt by one of the faces 55,which action will result in positively operating such bolt to shift the lever 52 at the proper time.

I have illustrated in the present case a somewhat different connection between the leadscrew 7 and the tool-carriage from that shown in the machine illust-rated in myprior patent hereinbefore mentioned. In this case the carriage C supports a divided nut, (indicated herein in a general way by 60,) and the two halves of this nut may be closed upon ordisengaged from the lead-screw by a suitable device, such as the right and left end thumbscrew shown at 61, the operation of which will be obvious. When the nut is released lVhe-n the bolt is thus forced back in a bearingt on the tool-carriage and preferably operated by means of the usual ballE lever 65. lVhen the split nutis released from the 'lead-screw and this lever 65 is turned, the tool-carriage and its various parts may be shifted rapidly along the bed. t

The operation of a machine constructed in accordance with my present improvements as shown herein is as follows: A tap of ordinary construction vwhich is to `be changed into a tap of the type shown in my patent first hereinbefore mentioned should be clamped in place in the usual manner between the head-stock and the tail-stock. It being understood that the tool-carriage is at the beginning of its range of travelthat is, at the extreme righthand end of the machine shown in Fig. 1

the milling-cutter is then adjusted at the p proper angle and clamped in place by the holdin g-nut 27, after which the cutter is adjusted to the proper position relatively to the tap by the `adjusting-screw 2G. The machine being started then by the rotation of the pulleys P and P and the milling-cutter of course being rotated by its pulley, movement will be transmitted to the work-spindle and the other operating` parts by the pulley P, which at this time is clutched to the shaft 17. Through the connections from this shaft 17 the lead-screw 7 is rotated preferably at a relatively lowspeed by the pulley P, and the slow traveling movement of the carriage C begins. As the camwheel W rotates the rock-arm 35/ is gradually shifted away from the axis of the cam-Wheel by riding up the ascent of one of the cams w, and thereupon the shafts 35 and 39 and the rock-arm 39 are oscillated correspondingly and the tool-holder 7L is positively advanced toward the'tap to enable the cutter m to begin the cutting operation on said tap, which at this time is also turning slowly in the same direction as the cutter. Then this cutting operation has been finished, the proper cam, which has been shifting the slide 50 toward the axis of the work-holder, will carry such slide through the last part of such movement, and thereby move the clutch-actuator 51 with it and enable such actuator to shift the lever 52to uncouple the pulley P and clutch the high-speed pulley P to the shaft 17. Thereupon, of course, the sleeve 9 and theworkholder 6 will be rotated at a more rapid rate of speed, and this will result in turning the tap to bring the second succeeding wing thereof into position to be operated upon by the millingcutter,which du ring su chmovement of the tap will be returned quickly to its normal idleposition, tirst, by reason of the fact that the arm ICO IIE)

35 will ride down the let-off face of the proper cam-w, and, second, because the released reacti-ve spring 3l will then become effective to return the tool-holder quickly. Shortly after the shifting of the clutch in the manner just described one of the cams w comes into contact with the pin 45' on the arm 4:5 and begins to shift such arm and the slide 50 in the opposite direction to that just described-that is, the g clutch-actuator 50 is shifted toward the lever 52, as shown in Fig. l, and at the proper time will ride past the point of said lever and reverse the same to uneouple the pulley P and reclutch the pulley P to the shaft 17, Wherenpon the Work-holder G and the sleeve l9 will be again rotated at the slow rate of speed and thefmilling-cutterm will be advanced toward the Work'to mill out anothertooth of the tap. This action just described'will be repeated and a cut taken for every other tooth of the tap until the end of the spiral in which the ually by the lead-screw the milling-cutter will be shifted alternately into and out of y icombination, with a tap-holder and with auengagement with the teeth of the tap, it operating to out alternate teeth in alternate Wings and to skip the intermediate teeth in the other wings. Moreover, as the carriage moves the tool-holder Will gradually recede from the longitudinal axis of the tap to an extent determined bythe taper of the tap and the angular position of the taper-guide 23; The machine will continue to operate automatically to advance and retract the milling-cutter until every other tooth in the tap is entirely cut away and the tap presents throughout the appearance shown at the right hand in Figs. l and 2, whereupon the split nut 60 may be released from the leadscrewv by turning the right and left `hand screw 6l, and the ball-lever G5 may then be brought into use to return the tool-carriage to its initial position for operating upon another tap.

lHaving described my invention, I claiml. In a machine of the class specified, the combination, with a tapholder and With mechanism for rotating the same, of a toolholder; arotary milling-cutter carried by said tool-holder; means for adjusting said cutter p relatively to the tap to correspond to the pitch of the teeth of the latter; and tool-holder-actuating means for shifting the tool-holder toward and from the tap-holder a plurality of times during each complete rotation of the latter, and for carrying the milling-cutter into and out of engagement with alternate Wings of thetap.

2.V In a machine of the class specified, the combination, With a tap-holder and With automatically-operative mechanism for rotating the same, of a tool-carriage; means for imparting a feed movement to said carriage; a tool-holder on said carriage; a rotary millingcutter carried by said tool-holder; means for adjusting said cutter relatively to the tap to llatter; and tool-holder-actnating means for shifting the tool-holder,toward and from the ,tap-holder a plurality of times during each- `complete rotation of the' latter, and for car- `rying the milling-cutter into andvontof engagement with alternate Wings of-the tap.

3. In a machine of the class specified, the combination, with a tap-holderand with auf'tomaticallyoperative mechanism for rotat- ,ing the same, of a tool-carriage; means -for a tool-holder on said carriage; a tool-holderimparting a feed movement to said carriage;

guide disposed at an acute angle to the longitudinal axis of the tap-holder; a rotary millin g-cu tter carried by said tool-holder; means j for adjusting said cutter relatively to the tapto correspond to the pitch of the teeth of the latter; and tool-holder-actuating means for `'shifting the tool-holder toward and from the ltap-holder a plurality of times during each fcomplete rotation of the latter, and for carrying the milling-cutter into and out of en'- gagement With alternate Wings of the tap.

il. In a machine of the class specified, the

tomatically-operative mechanism for rotat- `ing the same, of a tool-holder; a rotary milliing-cutter carried by said tool-holder; means Vfor rotating the milling-cutter in operative :relation With, and in l[he same direction as the tap While the latter is rotating; means for tation of the latter, and for carrying the milliing-cutter into and out of engagement With ialternate Wings of the tap.

. In a machine of the class specified, the

i combination, with a rotary tap-holder, of a i, tool-holder; a rotary milling-cutter carried by said tool-holder; and differential-feed toolholder-actuating means for shifting the tool- I,holder toward the tap-holder at one rate of "speed a plurality of times during each com- ;plete rotation of the latter, and for carrying {the milling-cutter into engagement With the fwings of the tap, and for returning the toolholder and the cutter at a higher rate of speed.

6. In a machine of the class specified, the

Icombination, with a, rotary tap-holder, of a tool-holder a rotary milling-cutter carried by said tool-holder; differential drivingmechan- `ism for rotating the tap-holder at different IOO y, y v 627,299 r said tap-holder and operative for shifting thev tool-holder toward and from the tap-holder a plurality of times during cach completerotai,

tion of the latter, and for carrying the milling-cutter into and out of engagement with the Wings of the tap.

S. In a machine ofA the class specilied, the

` combination, with a tapaholder and with automa'tically-operative mechanism for rotatingthe same, of a tool-holder; a rotary millingcutter carried by said tool-holder; a rotary tool-holder-actuating cam-shaft having a pl nrality of cams operative for shifting the toolvholder toward the tap a plurality of'ti mes during each complete rotation of the latter, and for carrying the milling-cutter into engagement with the wings ofthe tap, each of said cams having a quick'let-oit face; and an independent tool-holder-actuating spring for imparting a quick-return movement to the tool-holder on the release of the latter, and for withdrawing the cutter from engagement with the wings of the tap,

i). In a machine of the class specified, the combination, with a tapholder and with automatically-operative mechanism for rotatingthe same, of a tool-holder; a tool-carriage; mechanism for imparting a feed movement to the tool-carriage; a cross-feed slide supported on said carriage; a react-ive slidabie tool-holder su pported on said cross-feed slide; a rotary milling-cutter carried by said toolholder; and means for automatically shifting the tool-holder toward the tap-holder a plu rality of times during each complete rotation of the latter, and for carrying the milling-cutter into engagementI with the wings of the tap.

10. In a machine of the class specified, the combination, with a tap-holder and With automatically-operative mechanism for rotating the same, of atool-hold er; a tool-carriage; mechanism for imparting a feed movement to the tool-carriage; areactive tool-slide supported by said carriage; a tool-holder adjustable on said tool-slide; a rotary millingcntter carried by said tool-holder; and means for automatically shit tin g the tool-holder toward the tap-holder a plurality of times during each complete rotation of the latter, and for carryn ing the milling-cutter into engagement with the Wings of the tap.

11. In a machine ot the class specified, the combination, with a tap-holder and with automatically-operative mechanism for rotating the same, of a tool-holder; atool-carriage;

tool-holder; and means for automatically shifting the tool-holdertoward the tap-holder a plurality `of times during each complete rotation of the latter, and for carrying the milling-cutter into engagement with ythe wings of` the tap.

12. In a machine of the class specified, the combination, with a tap-holder and with automatically-operative mechanism for rotating the same, of a tool-holder; a tool-carriage;

mechanism for imparting a feed movement to the tool-carriage; a reactive tool-slide su pported by said carriage; a duplex tool-holder one of the membersof which is adjustable longitudinally of said slide and the other in an arc of acircle; la rotary milling-cuttercar ried by said tool-holder; and means for automatically shifting the tool-holder toward the tap-holder a plurality of times during eachV complete rotationot the latter, and for carrying the milling-cutter intov engagement with the wings of thetap. n

13. In a machine of the class specified, the

combination, with a tap-holder and with au-A i ICO bular slide toward the tap-hold er a plurality member having a plurality of cams, of a pair ot' alternately operative driving members controlling the rotation of the driven member; a clutch cooperative with said driving members alternately; a clutch-operating slide operative by said cams; and a clutch-shift ing lever connected with said clutch and operative by said slide.

16. The combination, with a rotary driven member having a plurality of cams, of a pair of altern ately-operative drivin g members controlling the rotation of the driven member; a clutch cooperative with said driving members alternately; a clutch-operating slide 0perative by said cams; and a spring-pressed clutch-actuator carried by said slide.

17. The combination, with a rotary driven member having a plurality of cams, of a pair of alternately-operative driving members con- IIO trolling the rotat-ion of the driven member; a clutch coperative With'said driving members alternately; a clutch-operating slide op erative by said cams; aspring-pressed clutch- -actuator carried by sai-d slide; and a clutchshifting lever substantially in alinement with and operative by said actuator.

18. yThe combination, With a rotary driven member having a plurality ot' camsot a pair of alternately-operative driving members controlling the rotation of the driven member; a` clutch eoperative with said driving members alternately; a clutch-operating slide operative by said cams; a spring-pressed clutchf actuator carried bysaid slide; and secondary clutch-actuating means for positively operatingy said clutch-actuator.

19. The combination, with a rotary driven member having a plurality of cams, of a pair of alternately-operative drivi n gmembers controlling the rotation of the dri-ven member; a clutch coopera-tive With said driving members alternately; a clutch-operative slide operative by said cams; a spring-pressed clutch-actuator carried bysaid slide; and an operatingface in the path of movement of saidclutchactuator for positively shifting the latter.

20. The combination, with a rotary driven member having two sets of cams, of a pair of alternately-operative driving members controlling the rotation of the driven member; a clutch cooperative with said driving members alternately; a clutch-operating slide shiftable in opposite directions alternately by said cams; and aspring-pressed'clutch-actuator carried by said slide and operative in a direction transverse to the path of'movement of the slide for shifting the clutchin opposite directions alternately.

2l. The combination, With a rotary driven member having two sets of cams, of a pair of alternately-operative driving members controlling the rotation of the driven member; a clutch cooperative with said driving members alternately; a clutch-operating, slide shi'ftablein opposite directions alternately by said cams; aspring-pressed elutcl1-actuator carried by said slide and operative in a direction transverse tothe pathof movement of the slide for shifting the clutch in opposite directions alternately; and a pair of operating-faces at opposite ends of the normal path of movement of the clutch-actuatorand operative alternately for shifting the latter.

22. The combination, with adriven member, of a tool-holder; a pair of alternately-operative driving members controlling the rotation of the driven member; a clutch coperative with said driving members alternately and eontrolledby the rotation of the driven member; and tool-holder-actuatin-g means also controlled by said driven member and operative for shifting the tool-holder into and out of Working position a plurality of times during each complete rotation of the driven member. l

23. The combination, with a driven member havin g three se ts of cams, of a tool-holder; fa pairof alternatelyoperative driving members controlling.,r the rotation of the driven member; a clutch cooperative with said driving members alternately and-operative in opposite .directions alternately by two of said sets of cams; and tool-holder-actuating means controlled by the-third set of cams and operative for shifting the tool-holder into Working position a plurality of ti mesduring each complete rotation of the driven member.

24. Thecombination, with a driven member having three setsof e'quidistant Cams, of a tool-holder; a pair of alternatelyoperative driving members controlling the rotation of thedriven member; a clutch coperative with said driving members alternately and operati ve in opposite directions alternately by two of said sets of cams; and tool-holder-actuating means controlled by the third set of cams Working position a plurality of times during each complete rotation of the driven member.

ber having three sets of cams, of a tool-holder; a pairof alternately-operativehigh-speed and low-speed driving-pulleys controlling the ro tationv of the driven member; a clutch coperative with said pulleys alternately and 0perative in vopposite directions alternately by two of said sets of cams; and tool-holder-actua-ting means controlled by the third set of cams and operative for shifting the tool-holder into Working position a plurality of times lduring each complete rotation of the driven member.

26. The combination, with a driven member having three sets of cams, ofa tool-holder; a pair of alternately-operative driving members controlling the rotation ofthe driven member; a clutch cooperative with said driving members alternately'and operative in opposite directions alternately by two of said 4sets, of' cams; tool-holder-actuating means icontrolled by the third set of cams andoperative for shifting the tool-holder into Work- ;ingposition a plurality of times at one rate gof speed during each complete rotation of the i driven member; and means for returning the l tool-holder to its idle posi-tion at a higher rate loi' speed.

ber, of a tap-carryin g work-spindle; a rotary driven member having a circuitof cams; a tWo-to-one gear-train between said Work-spinidle and said driven member; a tool-holder; a rotary` milling-cutter carried by said toolholder; and tool-holder-actuatin g means controlled bysaid cams and operative for shiftin g l; the tool-holder toward the Work-spindle aplnirality of times during each complete rotation lof the latter, and for carrying'the cutter into @engagement with alternate Win gs of the tap. FRANK G. ECI-IOLS.

. Witnesses:

FRANCIS I-I. RICHARDS,

GEORGE A. HOFFMAN.

and operative for shiftingthetool-holder into.

25. The combination, With. a driven mem- IOC) IIO

l 27. The combination, with a driving mem- 

